The Future of GIS. Software

GIS is in its formative years. All types of users have accepted the technology, and it is a worldwide multibillion-dollar industry. This acceptance has created a great demand in digital geo-spatial information and improved technology to be satisfied in the near future.

High-resolution (1 meter or less) commercial satellites and multisensor platforms (for example, global position system technology, inertial navigation systems, high-resolution digital images, laser scanners, multispectral, hyperspectral, etc.) generating high-resolution images, positions, attitude, and so on mobile mapping technology generating high-resolution images and geo-spatial positions and attitude; efficient analog-to-digital data conversion systems; and so forth are some of the promising approaches to the generation of geo-spatial data.

At the same time, the use of the Internet is creating new opportunities and new demands in GIS. Opportunities generated by the Internet include allowing access to a very large number of datasets all over the world and World Wide Web mapping. World Wide Web mapping is based on the easy-to-use browser-based format that is both simple and cost-effective to implement, which allows the common individual to use the Web to access maps and GIS-based data. Sophisticated GIS applications become usable by everyone over the Internet.

New demands in GIS generated by the Internet include better and faster analysis and query tools as well as better visualization systems; better tools to access and merge remote data without creating new datasets are needed; an integrated format for raster, vector, video, panoramic views, audio, spectral, multispectral data, and so on is fundamental, which will allow integration of multimedia data into a single format and will simplify the storage and manipulation of geo-spatial data.

The Open GIS Consortium will help in satisfying some of the above demands. The Open GIS Consortium is an international industry consortium founded in 1994 by several GIS organizations. The purpose was to address the issue of incompatibility standards in GIS technology. Today, more than 220 companies, government agencies, and universities participate in a consensus process to develop publicly available specifications for interfaces and protocols that enable interoperable geo-processing services, data, and applications.

The vision of the Open GIS Consortium is a ‘‘world in which everyone benefits from geographic information and services made available across any network, application, or platform,’’ and its mission ‘‘is to deliver spatial interface specifications that are openly available for global use’’ (22). The Open GIS Consortium envisions the integration of GIS data and technology into mainstream computing and the widespread use of standards-compliant GIS software throughout the information infrastructure.

Current specifications from the Open GIS Consortium include (1) Reference Model; (2) Abstract Specification; (3) Implementation Specifications; (4) Recommendation Papers; (5) Discussion Papers; and (6) Conformant Products. The Open GIS Consortium is currently working on eight interoperability initiatives (22), and their effort will continue for several years to come.

GIS capabilities will improve, which is reflected in the large amount of ongoing research, published results, and products and services. This work includes visualization, user interfaces, spatial relation languages, spatial analysis methods, geo-spatial data quality, three-dimensional and spatio-temporal information systems, open GIS software design and access, and more. A search in the Internet of the topic ‘‘visualization research’’ produced than 300,000 hits.

Noticeable among them are entries from AT&T Information Visualization Research Group (23) and the Stanford Computer Graphics Laboratory of Stanford University (24). In the field of ‘‘user interfaces,’’ a search in the Internet found less than 200 hits. However, there are many professional associations such as the User Interface Engineering, which in 2003 had its eighth Conference. In the case of ‘‘Spatial Relation Languages, we received than 20,000 hits in our Internet search.

Many interesting topics, such as visual languages for static and dynamic cases; Spatial Query Languages; Spatial reasoning; and so on are found under this topic. In the area of ‘‘Spatial Analysis Methods,’’ we found more than 230,000 hits. Spatial analysis has been around for a long time, but GIS makes its use easy. Spatial data mining is a new topic in spatial analysis and generates a lot of interest among researchers. Data mining is discovering knowledge from large databases. As indicated by Ramirez (25), ‘‘simply put, data mining is basically a modeling activity.

You need to describe the data, build a predictive model describing a situation you want to investigate based on patterns determined from known results, and verify the model. Once these things are done, the model is used to test the data to see what portions of the data satisfy the model. If you find that the model is satisfied, you have discovered something new about your data that is of value to you.’’ We found more than 46,000 hits searching specifically for ‘‘Spatial Data Mining’’ on the Internet.

This topic is of great interest that would provide a major payoff to the user of geo-spatial data. Searching for the topic ‘‘GeoSpatial Data Quality,’’ we found more than 2500 hits on the Internet. Many of these hits are related to metadata, but efforts in other aspects of data quality and visualization of geo-spatial quality were also found. The search of ‘‘Three Dimensional and Spatio-Temporal Information Systems’’ on the Internet was conducted in two steps. We searched for ‘‘Three-Dimensional Information Systems’’ and received than 290,000 hits.

We found a large variety of subjects such as machine vision, three-dimensional databases, and three-dimensional display systems that are more or less related to GIS. We also searched for ‘‘Spatio-Temporal Information Systems’’ and received than 16,000 hits. It is obvious that the subject of three-dimensional information systems is more advanced than spatio-temporal systems, but there is ongoing research in both subjects.

Finally, in the topic of ‘‘Open GIS Software Design and Access,’’ we discussed earlier the work of the Open GIS Consortium that is the best link to this topic. These research and development efforts will result in better, reliable, faster, and more powerful GIS.

Several peripheral hardware components may be part of the system: printers, plotters, scanners, digitizing tables, and other data collection devices. Printers and plotters are used to generate text reports and graphics (including maps). High-speed printers with graphics and color capabilities are commonplace today.

The number and sophistication of the printers in a GIS organization depend on the amount of text reports to be generated. Plotters allow the generation of oversized graphics. The most common graphic products of a GIS system are maps. As defined by Thompson (1), ‘‘Maps are graphic representations of the physical features (natural, artificial, or both) of a part or the whole of the earth’s surface.

This representation is made by means of signs and symbols or photographic imagery, at an established scale, on a specified projection, and with the means of orientation indicated.’’ As this definition indicates, there are two different types of maps: (1) line maps, composed of lines, the type of map we are most familiar with, usually in paper form, for example a road map; and (2) image maps, which are similar to a photograph. Plotters able to plot only line maps are usually less sophisticated (and less expensive) than those able to plot high-quality line and image maps.

Plotting size and resolution are other important characteristics of plotters. With some plotters it is possible to plot maps with a size larger than one meter. Higher plotting resolution allows plotting a greater amount of details. Plotting resolution is very important for images. Usually, the larger the map size needed, and the higher the plotting resolution, the more expensive the plotter.

Scanners are devices that sense and decompose a hardcopy image or scene into equal-sized units called pixels and store each pixel in computer-compatible form with corresponding attributes (usually a color value per pixel). The most common use of scanning technology is in fax machines. They take a hardcopy document, sense the document, and generate a set of electric pulses. Sometimes, the fax machine stores the pulses to be transferred later; other times they are transferred right away.

In the case of scanners used in GIS, these pulses are stored as bits in a computer file. The image generated is called a raster image. A raster image is composed of pixels. Generally, pixels are square units. Pixel size (the scanner resolution) ranges from a few micrometers (for example, five) to hundreds of micrometers (for example, 100 micrometers). The smaller the pixel size the better the quality of the scanned images, but the larger the size of the computer file and higher the scanner cost. Scanners are used in GIS to convert hardcopy documents to computer-compatible form, especially paper maps.

Some GIS cannot use raster images to answer geographic questions (queries). Those GIS that can are usually limited in the types of queries they can perform (they can perform queries about individual locations but not geographic features). Most queries need information in vector form. Vector information represents individual geographic features (or parts of features) and is an ordered list of vertex coordinates. Figure 1 shows the differences between raster and vector.

Digitizing tables are devices that collect vector information from hard-copy documents (especially maps). They consist of a flat surface on which documents can be attached and a cursor or puck with several buttons, used to locate and input coordinate values (and sometimes attributes) into the computer. The result of digitizing is a computer file with a list of coordinate values and attributes per feature. This method of digitizing is called ‘‘heads-down digitizing.’’

Currently, there is a different technique to generate vector information. This method uses a raster image as a backdrop on the computer terminal. Usually, the image has been geo-referenced (transformed into a coordinate system related in some way to the earth). The operator uses the computer mouse to collect the vertices of a geographic feature and to attach attributes. As in the previous case, the output is a computer file with a list of coordinate values and attributes for each feature. This method is called ‘‘heads-up digitizing.’’

Software and its use. Software, as defined by the AGI dictionary (2), is the collection of computer programs, procedures, and rules for the execution of specific tasks on a computer system. A computer program is a logical set of instructions, which tells a computer to perform a sequence of tasks. GIS software provides the functions to collect, store, retrieve, manipulate, query and analyze, and display geographic information.

An important component of software today is a graphical user interface (GUI). A GUI is set of graphic tools (icons, buttons, and dialogue boxes) that can be used to communicate with a computer program to input, store, retrieve, manipulate, display, and analyze information and generate different types of output. Pointing with a device such as a mouse to select a particular software application operates most GUI graphic tools. Figure 2 shows a GUI.

GIS software can be divided into five major components (besides the GUI): input, manipulation, database management system, query and analysis, and visualization. Input software allows the import of geographic information (location and attributes) into the appropriate computer-compatible format. Two different issues need to be considered: how to transform (convert) analog (paper-based) information into digital form, and how to store information in the appropriate format.

Scanning, and heads-down and heads- up digitizing software with different levels of automation, transforms paper-based information (especially graphic) into computer-compatible form. Text information (attributes) can be imported by a combination of scanning and character recognition software, and/ or by manual input using a keyboard and/or voice recognition software. In general, each commercial GIS software package has a proprietary format, used to store locations and attributes. Only information in that particular format can be used in that particular GIS.

When information is converted from paper into digital form using the tools from that GIS, the result is in the appropriate format. When information is collected using other alternatives, then a file format translation needs to be made. Translators are computer programs that take information stored in a given format and generate a new file (with the same information) in a different format. In some cases, translation results in information loss.

Manipulation software allows changing the geographic information by adding, removing, modifying, or duplicating pieces or complete sets of information. Many tools in manipulation software are similar to those in word-processors: create, open, and save a file; cut, copy, paste, undo graphic and attribute information.

Many other manipulation tools allow drafting operations of the information, such as: draw a parallel line, square, rectangle, circle, and ellipse; move a graphic element, change color, line width, line style. Other tools allow the logical connection of different geographic features. For example, geographic features that are physically different and unconnected, can be grouped as part of the same layer, level, or overlay (usually, these words have the same meaning).

By doing this, they are considered part of a common theme (for example, all rivers in a GIS can be considered part of the same layer: hydrography). Then, one can manipulate all features in this layer by a single command. For example, one could change the color of all rivers of the hydrography layer from light to dark blue by a single command.

Database management system (DBMS) is a collection of software for organizing information in a database. This software performs three fundamental operations: storage, manipulation, and retrieval of information from the database. A database is a collection of information organized according to a conceptual structure describing the characteristic of the information and the relationship among their corresponding entities (2).

Usually, in a database there are at least two computer files or tables and a set of known relationships, which allows efficient access to specific entities. Entities in this concept are geographic objects (such as a road, house, and tree). Multipurpose DBMS are classified into four categories: inverted list, hierarchical, network, and relational.

Healy (3) indicates that for GIS, there are two common approaches to DBMS: the hybrid and the integrated. The hybrid approach is a combination of a commercial DBMS (usually, relational) and direct access operating system files. Positional information (coordinate values) is stored in direct access files and attributes, in the commercial DBMS. This approach increases access speed to positional information and takes advantage of DBMS functions, minimizing development costs.

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